1. Field of Invention
This invention relates to an animal feed supplement and, in particular, to a preservative coating for a solid animal feed supplement, and a method of packaging the solid supplement.
2. Brief Statement of the Prior Art
Molasses has been used for many years as an animal feed supplement together with additives such as phosphoric acid and feed nutrients such as urea, fats, and the like. Solid materials such as cottonseed meal have also been suspended in the molasses; however, difficulties have been experienced with maintaining a stable suspension of solid materials. The liquid materials have been fed by application to fodder or by free choice feeding on lick-wheels.
Feed supplements have also been manufactured and marketed as solid blocks. The earliest blocks were pressed blocks which were formed by compressing mixtures of molasses and dry feed ingredients. Poured blocks in which the ingredients are mixed with molasses and poured into cardboard cartons where they solidify are more recent developments. The earliest commercial poured block was prepared by evaporative heating of the molasses similar to candy manufacturing as described in U.S. Pat. No. 3,961,081. This block lacked water resistance, and melted at elevated storage temperatures.
The most recent advances in supplement have been the poured chemical blocks, in which additives are used to gel molasses and form water-resistance solids. Large amounts of calcium oxide or magnesium oxide have been added to molasses and the mixtures have been heated to form solid supplements in the manner described in New Zealand Patent Specification No. 170,505.
Entirely chemically gelled and hardened poured blocks and their manufacture are described in U.S. Pat. Nos. 4,027,043, 4,160,041 and 4,431,675. These blocks are prepared by the reaction of molasses, a soluble phosphate and the oxide or soluble salt of calcium and/or magnesium. No heating is required and the liquid mixture is poured into cardboard cartons for solidification. Maximum hardness is attained by using both calcium and magnesium oxides.
Another method of manufacture of a poured block is described in U.S. Pat. Nos. 4,171,385 and 4,171,386 in which the molasses is gelled with clay which is added with high shear agitation. Magnesium oxide is added to the liquid mixture and the hardness of the block can be increased by the addition of ferrous sulfate, as described in U.S. Pat. No. 4,265,916.
These products are intended for free choice or managed feeding. Unfortunately, all the aforementioned supplement blocks are affected to some degree by the environment. Usually the blocks lose from 1 to about 5 weight percent moisture in the few days immediately following their manufacture. In hot, dry climates, further loss of water can occur, to the extent that the blocks shrink and crack, resulting in an unattractive appearance. When exposed to elevated storage temperatures and high humidity, mold can also develop on the surface of the blocks, usually starting at the surface interface between the cardboard box and the block.